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United States Patent |
5,560,290
|
Kaneko
|
October 1, 1996
|
Safety apparatus in power press machine
Abstract
A safety apparatus is mounted to the side of a bed of a power press machine
on which an operator is positioned for ensuring safety of the operator of
the power press machine. The safety apparatus includes a table, for
supporting the front end portion of a workpiece, fitted so as to be
movable toward and away from the bed at substantially the same height as a
fixed mold set to the bed side and on the side of the bed where the
operator is positioned. A pair of two-hand operation type switches are
fitted to the front side portion of the table with a gap between them, and
are operated by both hands of the operator. A deactivating switch is
provided for deactivating the pair of two-hand operation type switches
when a movable mold set to slide portion side of the power press machine
approaches to within predetermined distance of the fixed mold set to the
bed side to provide a safety state. Thus, the slide portion is allowed to
operate only when the pair of two-hand operation type switches are
operated by both hands of the operator and are turned on.
Inventors:
|
Kaneko; Keiko (152, Hiromoto, Kamotacho, Okazaki, Aichi-ken, JP)
|
Appl. No.:
|
379206 |
Filed:
|
January 27, 1995 |
Foreign Application Priority Data
| Jan 28, 1994[JP] | 6-026343 |
| May 11, 1994[JP] | 6-123207 |
Current U.S. Class: |
100/352; 74/615; 192/131H; 192/134 |
Intern'l Class: |
B30B 015/28 |
Field of Search: |
100/53
74/615
192/131 R,131 H,134
|
References Cited
U.S. Patent Documents
3103270 | Sep., 1963 | Tilbury | 192/131.
|
3186256 | Jun., 1965 | Reznick | 74/615.
|
3276557 | Oct., 1966 | Brown | 192/134.
|
4113079 | Sep., 1978 | Wright | 100/53.
|
4177666 | Dec., 1979 | Du Bois et al. | 100/53.
|
4235324 | Nov., 1980 | Neild | 192/131.
|
Foreign Patent Documents |
59-199200 | Nov., 1984 | JP | 100/53.
|
6905597 | Oct., 1970 | NL | 100/53.
|
225742 | Dec., 1924 | GB | 192/134.
|
Primary Examiner: Gerrity; Stephen F.
Attorney, Agent or Firm: Wenderoth, Lind & Ponack
Claims
What is claimed is:
1. A safety apparatus, primarily mounted to the side of a bed of a power
press machine on which an operator is positioned, for insuring safety of
the operator of the power press machine, comprising:
a table, for supporting the front end portion of a workpiece, fitted so as
to be movable toward and away from the bed at substantially the same
height as a fixed mold set to said bed side and on the side of said bed
where the operator is positioned;
a pair of two-hand operation type switches fitted to the front side portion
of said table with a gap between them, and operated by both hands of the
operator; and
a deactivating switch for deactivating said pair of two-hand operation type
switches when a movable mold set to a slide portion side of the power
press machine approaches to within a predetermined distance of said fixed
mold set to the bed side to provide a safety state;
wherein the slide portion is allowed to operate only when said pair of
two-hand operation type switches are operated by both hands of the
operator and are turned ON.
2. A safety apparatus according to claim 1, which further includes a foot
switch operated by a foot of the operator, and wherein the slide portion
of the power press machine can be operated only when said pair of two-hand
operation type switches are operated by both hands of the operator and
turned on and when said foot switch is operated and turned on.
3. A safety apparatus according to claim 1, wherein said pair of two-hand
operation type switches are allowed to move only outward from positions
corresponding to said minimum gap set between them.
4. A safety apparatus according to claim 1, wherein said table can be
fitted and removed to and from table support members.
5. A safety apparatus according to claim 1, wherein a large number of pin
holes are defined in said table.
6. A safety apparatus according to claim 5, wherein a machining jig is
removably fitted to said table by utilizing said pin holes.
7. A safety apparatus according to claim 5, wherein a guard type safety
apparatus, having a construction in which a guard plate moves back and
forth in a direction orthogonal to the moving direction of said table by
the operation of an air cylinder, is fitted to said table by utilizing
said pin holes.
8. A safety apparatus according to claim 7, wherein said guard plate is
removably fitted to said table by utilizing said pin holes with a gap for
permitting the insertion of a sheet-like workpiece provided between said
guard plate and the upper surface of said table.
Description
BACKGROUND OF THE INVENTION
This invention relates to a safety apparatus in a power press machine,
which is fitted to the side of a bed of a power press machine on which an
operator is positioned, so as to insure safety of the operator.
Press work with a power press machine is extremely dangerous work which
might lead to permanent troubles for the operator. Therefore, according to
a law, the safety apparatus must be fitted to the power press machine. A
ray type, a two-hand operation type and a guard type safety apparatus are
typical examples of the safety apparatus of the power press machine, and
all of them have been widely used. However, they are not free from the
problems inherent thereto and are not yet entirely satisfactory.
The ray type safety apparatus comprises a projector and a light receiver,
detects a dangerous state when a part of the body of the operator
intercepts the rays of light, and stops the operation of a slide portion.
The law stipulates that the safety apparatus must effectively operate
through the whole stroke of the slide portion of the press machine, and
its fitting position is limited, too.
However, when the ray type safety apparatus is fitted to the fitting
position stipulated by the law and the press work is conducted, not only
the body of the operator but also a part of his clothes cut off (i.e.
interfere with) the rays of light. As a result, the operation of the press
machine is stopped, or the operator must be spaced away from the press
machine by a predetermined distance to execute the work. In other words,
safety is improved at the expense of working efficiency.
Depending on the content of the press work, there is the case where the
operator cannot help holding a part of the workpiece with his hand to
conduct the press work. In this case, a part of the body of the operator
cuts off the rays of light and the ray type safety apparatus starts
operating.
Further, when the workpiece is bent, no problem occurs when a flat
sheet-like operation is simply bent into an L shape by one bending
workpiece, but when the flat sheet-like work is bent around its four sides
in the same direction to obtain a box-like shape, the rays of light are
sometimes cut off by the portions which have been bent already.
Accordingly, depending upon the shape of the product produced by bending
the workpiece, the ray type safety apparatus cannot be used in some cases.
As described above, the ray type safety apparatus involves various problems
in the actual press operation.
In the two-hand operation type safety apparatus, the slide portion of the
press machine cannot be operated unless switches such as push buttons are
simultaneously operated by both hands. Moreover, each time one of the
hands is removed off from the switch during the operation of the slide
portion, the slide portion stops, or the slide portion is caused to stop
at each process step. Thus the operation cannot be re-started unless both
hands of the operator are removed from the switches for another process
step.
To further improve safety, there is a system which combines the two-hand
operation type switches with a foot switch. In any case, the bending work
cannot be carried out by one operator in the case of bending workpiece in
which a part of the work must be gripped by the hand. In this case, the
content of the bending work is greatly limited and the working efficiency
drops considerably.
The guard type safety apparatus is literally equipped with a guard for
preventing the hands of the operator from entering a molding portion of
the press machine. The guard is produced in such a manner as to correspond
to the shapes of the workpiece and the shaped article, and is fitted to
the molding portion. In this system, the guard which has been produced in
advance so as to correspond to the workpiece and to the shaped article
must be fitted again whenever the workpiece and the shaped article change.
Therefore efficiency of the process is low, and the cost of production of
the guard also increases overall cost.
For these reasons, various modifications are made by individual users in
the ray type and two-hand type safety apparatuses when using them, and
these modifications result in a large number of press accidents.
SUMMARY OF THE INVENTION
It is a first object of the present invention to improve safety without
lowering efficiency of the press work by making it possible to operate a
pair of two-hand operation type switches while the workpiece is gripped.
It is a second object of the present invention to expand the range of the
press work by disposing a large number of pin holes in a table for
supporting thereon a workpiece, which is movable with respect to a bed of
the power press machine, and removably fitting various machining jigs to
the table by utilizing these pin holes.
It is a third object of the present invention to improve safety of the
press work by preventing a part of the body of the operator from entering
the molding portion of the power press machine by utilizing plate which is
fitted to the table by utilizing the pin holes described above.
The present invention provides an operator-safety apparatus for use fitted
to the side of a bed of a power press machine on which the operator is
positioned. The apparatus includes a table for supporting the front end
portion of a workpiece, fitted so as to be movable toward and away from
the bed at the same height as a fixed mold set to the bed side and on the
side of the bed where the operator is positioned. A pair of two-hand
operation type switches fitted to the front side portion of the table with
a minimum gap set between them, and these are operated by both hands of
the operator. A deactivating switch is provided for deactivating the pair
of two-hand operation type switches when a movable mold set to a slide
portion side of the power press machine approaches to within a
predetermined distance of the fixed mold set to the bed side to provide a
safety state. The slide portion is allowed to operate only when the pair
of two-hand operation type switches are operated by both hands of the
operator and are turned ON.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an overall perspective view of a safety apparatus for a power
press machine according to the present invention.
FIG. 2 is a plan view of the safety apparatus.
FIG. 3 is a front view of the safety apparatus.
FIG. 4 is a side view of the safety apparatus.
FIG. 5 is an enlarged sectional view taken along a line 5--5 of FIG. 2.
FIG. 6 is an enlarged sectional view in a state where a table 4 is removed
from a pair of table support members 5.
FIG. 7 is a sectional view taken along a line 7--7 of FIG. 5.
FIG. 8 is a front view of a portion of a push button switch S.sub.1.
FIG. 9 is a sectional view taken along a line 9--9 of FIG. 8.
FIG. 10 is a perspective view of a part of the table 4 and a work receiving
pin P.sub.1.
FIG. 11 is a perspective view of a work receiving pin P.sub.2.
FIG. 12 is a perspective view of a work receiving pin P.sub.3.
FIG. 13 is a plan view in a state where bending work of a workpiece W.sub.1
has started.
FIG. 14 is a side view of the work W.sub.1.
FIG. 15 is a side view in a state where a final first bending portion
B.sub.1 of the workpiece is bent.
FIG. 16 is a side view in a state where an initial second bending portion
B.sub.2 of the workpiece W.sub.1 is bent.
FIG. 17 is a side view in a state where an initial third bending portion
B.sub.3 of the workpiece W.sub.1 is bent.
FIG. 18 is a side view in a state where a final second bending portion
B.sub.2 of the workpiece W.sub.1 is bent.
FIG. 19 is a side view in a state where a last third bending portion
B.sub.3 of the workpiece W.sub.1 is bent.
FIG. 20 is a plan view of the workpiece W.sub.1.
FIG. 21 is a perspective view of a box body formed by bending the workpiece
W.sub.1.
FIG. 22 is a plan view in a state where a side Gauge 28 is set to the table
4, positioning is made in a transverse direction of a workpiece W.sub.2
and press machining is conducted.
FIG. 23 is a side view of the workpiece W.sub.2.
FIG. 24 is a perspective view of the side gauge 28.
FIG. 25 is a partial enlarged view of an deactivating switch S.sub.3.
FIG. 26 is an operation circuit diagram of the safety apparatus according
to the present invention.
FIG. 27 is a perspective view in a state where a guard plate 35 operated by
an air cylinder 33 is mounted to the table 4 of the safety apparatus
according to the present invention.
FIG. 28 is a side view in a state where the guard plate 35 described above
is fitted to the table 4 of the safety apparatus according to the present
invention and a press operation is carried out.
FIG. 29 is a partial exploded side view mainly showing the fitting state of
the guard plate 35 to the table 4.
FIG. 30 is a substantial front view in a state where the guard plate 35
described above is fitted to the table 4 of the safety apparatus according
to the present invention.
FIG. 31 is an operation circuit diagram for operating the guard plate 35
use of the air cylinder 33.
FIG. 32 is a perspective view in a state where a single guard plate 36 is
fitted to the table 4 of the safety apparatus according to the present
invention.
FIG. 33 is a perspective view of the single guard plate 36.
FIG. 34 is a substantial front view in a state where the single guard plate
36 is fitted to the table 4 of the safety apparatus according to the
present invention.
FIG. 35 is a side view in a state where the single guard plate 36 is fitted
to the table 4 of the safety apparatus according to the present invention
and the press workpiece is carried out.
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be explained in further detail with
reference to embodiments thereof. A press machine to which the safety
apparatus according to the present invention is adapted has a construction
having a quick stop mechanism.
In FIGS. 1 to 4, a pair of guide bars 2 are horizontally supported on a bed
1 of a power press machine with a predetermined gap between them on the
side where an operator is positioned. A slider 3 is fitted to each of
these guide bars 2. A table support member 5 is integrally fitted to the
inside of each slider 3 in such a manner as to support a table 4 from
below and to be capable of adjusting the height of the table 4.
As shown in FIGS. 5 to 7, the table support member 5 comprises an outer
cylinder 6 integrally fitted to the slider 3 and an inner cylinder 7
fitted to the inside of the outer cylinder 6 upper half portion of an
adjustment bolt 8 is integrally welded to the inner cylinder 7, and its
lower end portion is meshed with a female screw member 9 fixed to the
inner periphery of the lower end portion of the outer cylinder 6. An
engagement hole 8a is defined at the upper end portion of the adjustment
bolt 8, and a pin insertion hole 7a is formed at the upper end portion of
the inner cylinder 7.
A connecting rod 11 is so disposed at a portion on the back of the table 4
immediately above the table support member 5 as to rotatably protrude
downward, and an engagement protuberance 11a meshing with the engagement
hole 8a of the adjustment bolt 8 is disposed at the lower end portion of
this connecting rod 11. A tool insertion hole 11b for inserting a tool for
rotating the connecting rod 11 is disposed on the upper end surface of the
connecting rod 11, and a pin insertion hole 11c is disposed at the central
portion of this tool insertion hole 11b.
The table support members 5 are integrally connected through a connecting
member 12. The connecting rods 11 protruding from the back of the table 4
are fitted into the inner cylinders 7 of the table support members 5,
respectively, and the engagement protuberances 11a are fitted into, and
meshed with, the engagement holes 8a of the adjustment bolts 8,
respectively. Furthermore, the connecting pin 14 is fitted into the pin
insertion hole 7a of the inner cylinder 7 and the pin insertion hole 11c
of the connecting rod 11. In this way, the table 4 can be removably fitted
to the pair of table support members 5. The table 4 can be removed from
the pair of table support members 5 by the mere steps of removing each
connecting pin 14 and then lifting up the table 4.
As shown in FIGS. 1, 3, 8 and 9, T grooves 15 are formed along the entire
portion of the end surface of the table 4 on the front side other than at
its center portion, and a head 16a of a T bolt 16 is fitted into the T
groove 15 on each side. A switch fitting plate 18 can be fixed to an
arbitrary position by this T bolt 16 and a nut 17.
The switch fitting plate 18 has an L shape, and a push button switch
S.sub.1 of a double-hand operation system is fitted to one of the ends of
the switch fitting plate 18. An engagement pin 19 is so fitted to the
other end as to protrude inward. In other words, a pair of right and left
push button switches S.sub.1 are disposed, and can be moved to, and fixed
at, arbitrary positions by loosening the nut 17 and moving the switch
fitting plate 18 to the right and left. Further, the position of the push
button switch S.sub.1 can be raised with respect to the table 4 as
indicated by two-dot-chain line in FIG. 9 by removing the nut 17, then
turning substantially 90.degree. the switch fitting plate 18, inserting
the engagement pin 19 into the T groove 15 and fixing the switch fitting
plate 18 to the front surface of the table 4.
The reason why the position of the push button switch S.sub.1 to the table
4 is elevated is to cope with a bending workpiece having a flange portion
as will be described later. The minimum gap between the pair of right and
left push button switches S.sub.1 is such that the switches cannot be
simultaneously operated by one hand of the operator and the gap is about
300 mm.
As shown in FIGS. 1, 2, 5 and 10, a large number of pin holes 21 are formed
at the depth of the table 4 with the standing position of the operator as
the reference. Work receiving pins P.sub.1 to P.sub.3 having various
shapes (see FIGS. 10 to 12) to cope with the bending workpiece having the
flange portion or side gauges 28 (see FIG. 24) for positioning the
workpiece in the transverse direction, or other machining Jigs, are
removably fitted into these pin holes 21.
In FIGS. 13 and 14, a V-shaped die 22 as a lower mold is set to the upper
surface of the bed 1 of the power press machine, and a punch 24 as an
upper mold is set to a slide portion 23 (see FIG. 25) disposed above the
bed 1.
A foot switch S.sub.2 operated by the foot of the operator is disposed at
the front part of the bed 1 on which the safety apparatus according to the
present invention is disposed, and as shown in the operation circuit
diagram of FIG. 28, the power press machine is constituted in such a
manner that it can be operated only when the pair of push button switches
S.sub.1 are pushed and turned ON and moreover, when the foot switch
S.sub.2 is pushed and turned ON.
The safety apparatus according to the present invention is equipped with an
deactivating switch for deactivating the pair of push button switches
S.sub.1 when the punch 24 lowers and approaches within a predetermined
distance of the die 22 to provide the safety state. In other words, as
shown in FIG. 25, a limit switch LS.sub.1 functioning as the invalid
switch is disposed in the proximity of the slide portion 23, and when the
slide portion 23 lowers, a dog 25 provided to the slide portion 23
actuates the limit switch LS.sub.1. The position of the dog 25 can be
adjusted so that the operation start position of the limit switch LS.sub.1
can be finely adjusted.
Next, the explanation will be given for the case where a workpiece W.sub.1
shaped by punching as shown in FIG. 20 is bent into a box shape shown in
FIG. 21. First, as shown in FIGS. 13 and 14, the insertion portions 26 of
the workpiece receiving pins P.sub.1 are fitted into a plurality of pin
holes 21 disposed in the table 4, and a tool (not shown) is fitted into
the tool insertion hole 11b of the connecting rod 11 from the upper
surface of the table 4. Next, the table 4 is lowered by turning the
connecting rod 11 in a predetermined direction, and adjustment is then
carried out so that the reception surface of a plurality of workpiece
receiving pins P.sub.1 fitted into the pin holes 21 at their insertion
portion 26 takes the same level as the die 22 set to the bed 1.
The gap between the switch fitting plates 18 to which the pair of push
button switches S.sub.1 are set to a gap which can grip the workpiece
W.sub.1, and the switch fitting plates 18 are turned by a predetermined
angle from the normal state of use so that grip of the workpiece W.sub.1
and the operation of the push button switches S.sub.1 can be
simultaneously made. (In the embodiment shown in the drawings, the push
button switches S.sub.1 exist at the highest position when the switch
fitting plate 18 is turned by 90.degree. from the normal state of use.)
In this way, the workpiece W.sub.1 is supported by a plurality of workpiece
receiving pins P.sub.1 and the die 22, and the distal end surface of the
workpiece W.sub.1 is butted against the back gauge 27 for the purpose of
positioning. In this state, as shown in FIGS. 13 and 14, the front side of
the workpiece W.sub.1 is gripped and its bending is carried out under the
posture where each push button switch S.sub.1 can be operated by both
hands of the operator.
In other words, while the operator grips the end portion on front side of
the workpiece W.sub.1 with both hands, the pair of push button switches
S.sub.1 are pushed and turned ON by both hands and the foot switch S.sub.1
is pushed and turned ON by his foot. Then, a signal for actuating the
power press machine is generated from the safety apparatus, the punch 24
as the upper mold lowers, and one of the end portions of the workpiece
W.sub.1 is bent.
In this instance, as the punch 24 lowers by a predetermined distance and if
one of the hands of the operator comes off from the push button switch
S.sub.1 before the safety state where the limit switch LS.sub.1 as the
deactivating switch operates, the actuation circuit of the press machine
is opened and punch 24 is stopped instantly. In this way, safety of the
operator is insured.
The above will be explained on the basis of the operation circuit diagram
of FIG. 26 of the safety apparatus according to the present invention.
When the pair of push button switch S.sub.1 are turned ON, the relay
R.sub.1 is energized and its a contact is closed. Here, if the foot switch
S.sub.2 is kept OFF, the relay R.sub.5 is energized and its a contact is
closed. Accordingly, because the relay R.sub.3 is energized, the relay
R.sub.2 is self-held while the pair of push button switches S.sub.1 are
ON. When the foot switch S.sub.1 is turned ON under this state, the relay
R.sub.4 is energized and each open/close signal of its a and b contacts is
inputted to the actuation circuit of the power press machine, so that the
press machine is actuated.
When either one of the pair of push button switches S.sub.1 is turned OFF
before the limit switch LS.sub.1 as the deactivating switch is turned ON
after the actuation of the press machine, the relay R.sub.1 is turned OFF,
each of the relays R.sub.3 and R.sub.4 is also turned OFF and the press
machine stops. When either one of the pair of push button switches S.sub.1
is turned OFF after the limit switch LS.sub.1 as the deactivating switch
is turned ON, the relay R.sub.2 is turned ON, the relay R.sub.3 is
self-held, and the relay R.sub.4 is not turned OFF. Accordingly, the press
machine maintains its operation.
When the foot switch S.sub.2 is turned OFF during the operation of the
press machine, the relay R.sub.4 is turned OFF. Accordingly, the press
machine stops without fail.
As described above, both hands of the operator always operate the pair of
push button switches S.sub.1 during the dangerous state after the
operation of the press machine but before the operation of the
deactivating switch (limit switch LS1), and safety of the operator can be
thus insured. When the foot switch S.sub.2 operated by the foot of the
operator is disposed as in the embodiment described above, the press
machine can be operated only when the pair of push button switches S.sub.1
and the foot switch S.sub.2 are all turned ON. Therefore, safety of the
operator can be further enhanced and at, the same time, a construction,
which prevents the operation of the press machine when only the foot
switch S.sub.1 is erroneously operated before the operation of the press
machine, can be accomplished.
After the first bending portion B.sub.1 at the four corners of the
workpiece W.sub.1 is finished as shown in FIG. 15, the workpiece W.sub.1
is supported between a plurality of work receiving pins P.sub.1 and the
die 22 while the flange-like first bending portion B.sub.1 after bending
is kept so as to face downward. The inside portion of each first bending
portion B.sub.1 is bent under this state in the opposite direction so as
to form the second bending portion B.sub.2, as shown in FIG. 16.
Thereafter, the third bending portion B.sub.3 is formed inside the second
bending portion B.sub.2 as shown in FIGS. 17 to 19, and the sheet-like
workpiece W.sub.1 can thus be bent and shaped into the box shape.
During the bending workpiece described above, the table 4 is allowed to
advance with the progress of machining. Because the front side of the
workpiece W.sub.1 is supported by a plurality of workpiece receiving pins
P.sub.1 fitted into the pin holes 21 of the table 4, the workpiece W.sub.1
can be supported without any problem even when the flange-like first
bending portion B.sub.1 faces downward as shown in FIGS. 16 and 17.
When the workpiece is simply bent, the front side of the workpiece may be
directly supported by the table 4 without using the workpiece receiving
pins.
Next, explanation will be given for the case where a rectangular workpiece
W.sub.2 is press-machined by positioning it in both depth-wise and
transverse directions, with reference to FIGS. 22 to 24. Two insertion
pins 29 which are to be fitted into the pin holes 21 disposed in the table
4 are integrally formed in the bottom surface of the side gauge 28 shown
in FIG. 24. As shown in FIGS. 22 and 23, two insertion pins 29 of the side
gauge 28 are fitted into the pin holes 21 of the table 4.
The table 4 is set at the same height as the die 22 and each push button
switch S.sub.1 is kept at the normal position as indicated by a solid line
in FIG. 8. Under this state, the distal end surface of the workpiece
W.sub.2 is butted against the back gauge 27' disposed at the depth of the
die 22 and its side surface is butted against the side gauge 28 set to the
table 4. In this way, the workpiece W.sub.2 can be positioned in both
depth-wise and transverse directions. One of the push button switches
S.sub.1 is operated by the hand gripping the front side of the workpiece
W.sub.2 and press workpiece is carried out.
The foregoing embodiments represent the case where the front end side of
the workpiece is supported by the workpiece receiving pins P.sub.1 to
P.sub.3 by fitting the work receiving pins P.sub.1 to P.sub.3 into the pin
holes 21 of the table 4 and the case where positioning in the transverse
direction of the workpiece is effected by fitting the side gauge 28 into
the similar pin hole 21. However, various machining jigs can be fitted
into the pin holes 21 of the table 4 in accordance with the content of the
press work.
As described above, in the safety apparatus according to the present
invention, a pair of push button switches S.sub.1 are fitted to the front
portion of the table 4 for supporting the front side of the workpiece.
Accordingly, the front end side of the workpiece can be gripped while the
pair of push button switches S.sub.1 are operated, and one operator alone
can safely execute the press workpiece without lowering the working
efficiency.
When various machining jigs are fitted to the table 4 by utilizing a large
number of pin holes 21 disposed in the table 4, the operations peculiar to
press machining such as support of the workpiece having a flange portion
facing downward, positioning in the transverse direction of the workpiece,
and so forth, can be carried out simply and easily and the range of the
press work can be expanded.
Next, the case where a guard type safety apparatus is removably fitted to
the table 4 will be explained as another utilization method of the pin
holes 4 disposed in the table 4. It is contimplated that embodiment will
insure safety of the operator when the operator feeds and removes the
workpieces by inserting and removing a part of his body into and from the
molding portion of the press machine.
In FIGS. 27 to 30, a fitting portion 31a having a ]-shaped section is
disposed at one of the end portions of a guard plate guide plate 31 in its
longitudinal direction and this fitting portion 31a is fitted from the
back side of the table 4. Two pins 32 are fitted into the pin hole 31b
disposed in the fitting portion 31a and into the pin hole 21 described
above, and in this way, the guard plate guide plate 31 is fitted to the
table 4.
An air cylinder 33 is supported by a cylinder support portion 31c mounted
at one of the end portions of the guard plate guide plate 31 in its
longitudinal direction. The lower end portion of the guard plate 35
comprising a transparent acrylic resin plate is fitted into the guide
groove 34 defined in the guard plate guide plate 31, and the distal end
portion of a rod 33a of the air cylinder 33 is interconnected to one of
the side end surfaces of the guard plate 35.
Accordingly, the guard plate 35 is caused to reciprocate in a direction
orthogonally crossing the moving direction of the table 4 as the rod 33a
of the air cylinder 33 moves back and forth, and the front surface of the
die 22' disposed on the bed 1 of the power press machine is opened and
closed by the guard plate 35.
While the guard plate 35 is open, the operator directly feeds and removes
the workpiece W.sub.2 to and from the die 22. Limit switches LS.sub.12,
LS.sub.13 for confirming closure and opening of the guard plate,
respectively, are disposed at both moving end portions of this guard plate
35 (see FIG. 30).
FIG. 31 is an operation circuit diagram for operating the guard type safety
apparatus described above, and the operation of this guard type safety
apparatus will be explained with reference to this diagram. Incidentally,
reference symbols LS.sub.11 and LS.sub.14 represent limit switches for
detecting the ascension end and descension end of the slide portion 23 of
the power press machine, respectively.
First, when the slide portion 23 of the power press machine exists at the
ascension end portion, the limit switch LS.sub.11 for detecting the
ascension end is turned ON and the guard plate 35 is kept closed. When the
guard plate opening confirmation button S.sub.2 is pushed under this
state, the relay R.sub.14 is energized and a self-holding circuit is
formed. Therefore, the a contact of the relay R.sub.14 connected in
parallel with the b contact of the relay R.sub.13 is closed, and the relay
R.sub.12 is energized. Due to this energized relay R.sub.12, its a contact
is closed, the solenoid 33b of the air cylinder 33 is energized, and the
guard plate 35 is opened.
When this guard plate 35 opens completely, the limit switch LS.sub.13 for
confirming opening of the guard plate is opened, and the relay R.sub.14 is
deenergized. However, because the limit switch LS.sub.12 for confirming
closure of the guard plate remains open, the relay R.sub.13 is
deenergized, its b contact is closed, and the relay R.sub.12 is kept
energized. Accordingly, the guard plate 35 remains open.
When the operator pushes the pair of push button switches S.sub.1 of the
double-hand operation type disposed on the table 4 under this state, the b
contact of the relay R.sub.4 (see FIG. 26) constituting the operation
circuit of the safety apparatus according to the present invention opens,
and the relay R.sub.12 is deenergized. As a result, the a contact of the
relay R.sub.12 opens the solenoid 33b of the air cylinder 33 is
deenergized, the guard plate 35 is closed, and the limit switch LS.sub.12
for confirming closure of the guard plate is turned ON.
Here, if the pair of push button switches S.sub.1 are turned OFF while the
guard plate 35 is being closed but the limit switch LS.sub.12 is turned
ON, the guard plate 35 is again opened. Accordingly, the push button
switch S.sub.1 must be kept pushed until the limit switch LS.sub.12 is
turned ON (until the guard plate 35 is completely closed).
When the guard plate 35 is closed and the limit switch LS.sub.12 is turned
ON, the relay R.sub.3 is energized and its b contact is turned OFF. As a
result, the relay R.sub.12 is turned OFF and the solenoid 33b of the air
cylinder 33 is not energized any more. Accordingly, even when the push
button switch S.sub.1 is turned OFF, the guard plate 35 is kept closed.
When the guard plate 35 is closed and the relay R.sub.13 is energized, the
a contact of the relay R.sub.13 is closed and its signal is inputted to
the actuation circuit of the power press machine. As a result, the press
machine is operated. The slide portion 23 lowers, the limit switch
LS.sub.11 for detecting the ascension end is turned OFF, the limit switch
LS.sub.14 for detecting the descension end is turned ON at the descension
end of the slide portion 23, the relay R.sub.14 is energized, and the
self-holding circuit is formed. Accordingly, the a contact of the relay
R.sub.14 is closed, the slide portion 23 reaches the ascension end, the
limit switch LS.sub.11 is turned ON, the relay R.sub.12 is energized and
the guard plate 35 opens. Incidentally, reference symbol S.sub.4 in FIG.
31 represents the switch for confirming closure of the guard plate.
As described above, the guard plate 35 is always closed during the
operation of the power press machine. Therefore, a part of the body of the
operator cannot enter the molding portion of the press machine and safety
of the operator can be insured.
The embodiment shown in FIGS. 32 to 35 executes machining of a sheet-like
workpiece W.sub.4 by removably fitting the single guard plate 36 to the
table 4 by utilizing the pin holes 21 formed in the table 4, and so
preventing a part of the body of the operator from entering the molding
portion of the press machine.
In other words, the guard plate 36 comprising the transparent acrylic resin
plate is integrally fitted into the groove portion of the upper surface of
a receiving member 37, and a pair of pins 38 having a step portion is so
implanted to the bottom surface of the receiving member 37 as to protrude
therefrom. When the small diameter portion 38a of the pair of pins 38 is
fitted into the pin hole 21 of the table 4, the guard plate 36 can be
fitted to the table 4. Since the pair of pins 38 have the step portion, a
predetermined gap 39 is defined between the upper surface of the table 4
and the lower surface of the receiving member 37 under this state as shown
in FIG. 34.
The sheet-like workpiece W.sub.4 is inserted into this gap 39 from the
front side of the table 4 and its distal end portion is placed on the die
22 disposed on the bed 1. While the front end portion of the workpiece
W.sub.4 is supported by both hands of the operator, the pair of push
button switches are operated and a predetermined operation is carried out.
When this single guard plate 36 is used, the press machine may be so
constituted as to be operated by only the operation of the foot switch
S.sub.2.
As described above, the sheet-like workpiece W.sub.4 can be supplied to the
portion of the die 22 from the gap 39 and because the front side portion
of the die 22 is always covered with the guard plate 36 and a part of the
body of the operator is prevented from entering the molding portion of the
press machine, safety can be insured without inviting trouble for the
press operation.
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